Acoustical tile



'Jam l1, 1949. s. s.w1LLEY E'TAL, 2,459,121

AVCOUSTCAL TILE Fnedvsept. 17, 194s WA TTQRNEY Patented Jan. 11, 1949 y'Ao/ous'rrcnr. TILE g t Grant S. WilleyyChicago, and 'Orcutt W.r Frost, Highland Park, Ill., assignors to United Statesv Gypsum Company, Chicago, Ill., 'a'rcorporation of Illinois Apphcatihseptember 17, 194s, serial No. 502,728

yfromme. (c1. 181-33) This invention pertainsv toan acoustical construction. More particularly it is directed to a fibrous acoustical base having a' decorative coating receptive surface and theprocess of making,

the same.

Though the principles underlying this inven`y i tion are adapted to the preferred type ofan acoustical base comprising brillated ligno 'cellulosic materials felted in a sheet form in accordance with conventional methods of formation, it is not this nature though it is somewhat impervious to the intention to limit the same to the preferred embodiment, since obviously, with slightchanges and modification, the principles underlying' this invention canbe adapted with equalfacility to other inorganic and Organic `fibrous acoustical f bases.

For a more complete understanding of the principles underlying this invention reference, should be had to the accompanying rdrawings forming a part hereof, in which Figure 1 is a perspectiveview of an acoustical tile madey in accordance with the principles of this invention.

Figure 2 is a transversesection taken along line 2--2 of Figure 1 showing as one preferred embodiment' the depth to which thegrrooyesare cutin the acoustical tile bOdy.` t

Figure 3 is taken along lines 343 of Figure 1, partly broken away to show a section throughone of the grooves and indicate but one type ofzperiphery or arc impressed within the acoustical base. f

Figure 4 shows in a partly 4broken away section another type'of arc of a semicircular nature,l that may be also impressed'dependingon other relative conditions inherently present inthe acoustical base.

Figure 5 illustrates in a transverse sectionfanother modification of this invention.

An acoustical base I0, preferably comprising feltejd ligno cellulose fibrous materials such as used in conventional insulation board is treated to a simultaneous application of heat and pressure to develop in the surface thereof an autogeneously formed thermo plastic resin that not only binds the fibrous material on the surface I2 to form a more dense, and decorative medium receptive plane but also maintains the contiguous area I2a at a greater density in comparison with interior I 2b. The development and formation of sound,` it is, however, more protective, resistant to scuffin'gand denting, and moreeasily adapted to use under erection conditions.

To form this surface yit is desirable that the ligno cellulosic blanks be placed in contact with a heated surface maintained under very slight pressure toprevent undue compression in the interior` I2b of the acoustical base Il).l If great pressure is applied the interior I2b has a tendency to densify asthe heat from the surface penetrates the depth of the acoustical base III.y In practice it was found desirable to use a temperature of about 485 F. to lcatalyse and aid in the formation of the autogeneously'created ligno cellulosic resins on the surface I2, and the surface contiguously underlying area I2a. The length of heat'and pressure application will vary with the nature of the base. Though kit is desirable to pre-dry the acoustical blanks, it is not essential since the open, cellular structure permits the ready escape 4 of, gases and water generated during the autogeneous Yformation of the thermo plastic ligno i capable of absorbing sound. In any event it is desirable that the depth of the cut or groove is be at least one half of the thickness of ther acousf tical base I0. v

- Inv practice the parallel grooves are formed in the acoustical base I0, and extend approximately this autogeneously created thermo plastic ligno one third of the Way across the face l2 of the acoustical base I Il. At this point 24, another series I8a, b, c, d, etc. set off `or staggered in relationship to the previous series Ilia, b, c, d, etc. is started across anotherapproximate third of the way of the face to the point 26. The ends of the series I8, a, b, c, d, etc. is slightly overlapped but not joined by ends of the series I6a, b, c,.d, etc. at point 2,4,

and by the lends of the series 20, a, b, c, d, etc. at point 26. This type of construction provides for more acoustical base material between the grooves I'B and I8 and prevents a transverse planeI of rcleavage or weakness along successive grooves at this junction. Obviously other patterns employp ing these principles can also be made.

To aid and reinforce this junction well as for other reasons given below, the end sides 30 of the grooves I6 near the points 24 and 26, as

well as at the edges of the acoustical base I0,

gradually slope I2 in a form of an arc to the bottom 28 of the groove. The substantially elliptical type arc of the groove (as shown in Figure 3) is obtained by impressing the cutting means (not shown) into the interior |2b and then moving the cutting means longitudinally the desired distance. This particular type of groove construction is particularly useful in slotting acoustical bases having a thickness of less than one inch.

Obviously another type is the circular arc as shown in Figure 4. lf relatively small diameter cutting saws are used, the proper depth can be readily reached without cutting longitudinally.

To finish the tile a bevel lil can be formed on all edges either during the pressing operations or at subsequent stages of operation before the application of coating compositions to the formed surface.

A slot 22 is also formed in at least two of the sides of the acoustical base l0 to provide a means for insertion of a bridgeclip (not shown) or other suitable retaining means, to attach the tile mechanically to the surface, such as a wall or a ceiling. In practice, it frequently is desirable to use an adhesive backing on the tile, which is then erected and retained in place by the adhesive.

The slope 32 curves gradually to the bottom 28 of the groove. Though the interior IZb of the acoustical base i0, is generally darker in color, it is, however, not noticeable at the distance normally encountered between the eyes and the ceiling or wall upon which it is installed. In the course of applying the paint, there is a tendency for the excess amount to gradually flow down the slope and come to the surface l2 at points 24 and 2S. It should be noted that an acoustical tile when in use as for instance on a ceiling is inverted and the slots or grooves I6 face the source of sound. Under those conditions, as well as when it is used on the wall the excess of the coating composition will obviously under influence of gravity flow down the slope 32 to the surface i2. This flow not only decorates the visible part of the groove and thereby blending it into the foreground to decrease its visibility, but also prevents excessive accumulation of the coating composition within the groove itself and thereby destroy or impair its sound absorbing characteristics.

At times it may be desirable to increase still further the sound absorption and decrease the effect of the depth shadow of the groove. This can be readily accomplished by slotting the grooves i6, diagonally from the surface I2, into the body I2b as shown in Figure 5. Of course, when this particular modification is erected on the wall it is desirable that the grooves point downwardly to eliminate collection of dirt and facilitate future redecoration.

In making acoustical tile according to the principles underlying this invention, the surface of a fibrous base such as ligno cellulose felted sheets is simultaneously treated with heat and pressure under conditions mentioned previously. In practice it is preferred to mold simultaneously the bevel Il while heat and pressure are applied to the surface. This process provides a smooth, suitable coating receptive surface. In the preferred mode of operation, the whole series of grooves are simultaneously cut by means of the desired number of high speed saws. Each series ofsaws is mounted on a common shaft or spindle which in turn is driven by a high speed electric motor. The slotted or grooved acustica] tile is then decorated in the customary manner, allowed to dry; and packaged for further disposition.

Though the above description describes in considerable detail the outstanding features and characteristics of the principles underlying this invention, it is obvious that many adaptations, extensions, modifications and uses can readily be discerned by a. person skilled in this art, and it is not intended to be limited to the specic embodiments described herein but only by the spirit of principles of this invention as indicated in the attached clams.

It is claimed:

1. A sound absorbent consisting essentially of interlaced fibrillated lignocellusic fibers formed into a rigid cellular porous mat, the said mat having on one surface therein a series of discontinuous, parallel slots, the said slots sloping within the body of said mat to within the other surface thereof.

2. The product of claim 1 wherein the said slots are substantially circular.

3. The product of claim 1 wherein the said slots are elliptical.

4. The product of claim 1 wherein the said grooves have a depth of not less than one-half of the thickness of said base.

GRANT S. WILLEY. ORCUI'I W. FROST.

REFERENCES CITED LThe following references are of record in the file of thispatent:

UNITED STATES PATENTS 

